Weekly JLC Physics Group Meeting
Place: 3F Bldg 3, KEK
Time: 10:30, 98/05/29
0.1) General Notifications
0.2) CDC R&D Status (Part II)
 General Notifications
[1-1] ACFA News Update (T.Matsui)
T.Matsui will visit IHEP, Tsinghua Univ. in China
as a delegate in the period of June 10-13.
A new PC on which the ACFA server resides will arrive
on June 1 and will be set up by H.Sendai soon after.
[1-2] KEKVAX (A.Miyamoto)
KEKVAX will be shut down in December.
 CDC R&D Status Part II (H.Kuroiwa)
H.Kuroiwa made a interim report on his analysis results from
the beam test at the Tanashi branch.
Items to study with the beam test data include:
(1) chamber signal properties as a function of
incident angles (theta, phi)
H.Kuroiwa is now concentrating on single-track data to attack
item (1). It was pointed out that there is often a trailing pulse,
which is smaller in size and width. The probability to get the
trailing pulses increases with the incident angles. So far he
(i) no correlation in pulse height between a main and its
(ii) trailing pulses, if there are more than one, have similar
shape and size.
(iii) the shape, not only the size, of the main pulse depends
on both theta and phi.
(iv) the arrival time difference between the main and the second
pulses clearly depends on phi (the angle in the plane
perpendicular to anode wires) but not that clearly on theta.
(v) The trailing pulses were not observed for an X-ray source
but were there for a beta-ray source.
The trailing pulses seem to be originating from real ionization
clusters in the presence of space charge effects due to the low
diffusion nature of CO2-Isobutane. More studies are needed,
though, to draw any solid conclusion.